The Bunker Buster Act of 2025 gives the President authority to help Israel prepare for potential military action against Iran's nuclear program. Specifically, it allows the U.S. to help build infrastructure in Israel to support large bunker-busting weapons called Massive Ordnance Penetrators (MOPs)—these are designed to destroy underground nuclear facilities. This includes constructing longer runways for aircraft that carry these weapons, providing the aircraft themselves, setting up storage for the munitions, and training Israeli personnel on how to use them.

The bill also allows the President to store these weapons in Israel or, under strict conditions, transfer them to Israeli control. Before transferring the weapons, the President must certify to Congress that it's vital to U.S. national security and that Iran is violating nuclear agreements or blocking international inspectors. Additionally, there's a "dual key" control system requiring the U.S. Secretary of Defense to personally approve any Israeli use of these weapons. The bill also authorizes joint U.S.-Israeli research to develop better weapons for destroying underground infrastructure, including nuclear facilities and Hezbollah weapons storage.

The bill's findings emphasize concerns about Iran's nuclear program, noting that Iran has enriched uranium to 60 percent purity (close to weapons-grade levels), has enough material for several nuclear bombs according to international standards, and has been expanding its missile program. The bill also references Israel's June 2025 military strikes against Iranian targets. However, the bill explicitly states it does not authorize military force against Iran—it only authorizes preparation and support activities.